Circuit interrupters



Dec. 22, 1959 w. FUST CIRCUIT INTERRUPTERS 3 Sheets-Sheet 1 Filed Oct. 14, 1957 Dec. 22, 1959 w. FUST CIRCUIT INTERRUPTERS 3 sheets sheet 2 Filed Oct. 14, 1957 R m w w Wm M Dec. 22, 1959 w. FUST 2,918,552

CIRCUIT INTERRUPTERS Filed Oct. 14, 1957 3 Sheets-Sheet 3 MM WW United States Patent CIRCUIT INTERRUPTERS Wilhelm Fust, Giessen, Germany, assignor to Voigt 8:

Haelfner Aktiengesellschaft, Frankfurt am Main, Germany Application October 14, 1957, Serial No. 690,160

Claims priority, application Germany October 20, 1956 17 Claims. (11. 2oo -147 This invention refers to circuit interrupters, or circuit breakers.

It is one object of this invention to provide a family of circuit interrupter-s, i.e. a basic design for circuit interrupters, applicable for a Wide range of voltage ratings, current ratings and interrupting capacity ratings.

Another object of the invention is to provide improved magnetic blow-outs, or improved magnetic arc extinguishing means, for circuit interrupters.

Another object of the invention is to provide air magnetic circuit breakers comprising means for elongating an arc, means for subdividing the relatively long arc into a plurality of shorter partial arcs, and means for rotating said plurality of partial arcs by the action of magnetic fields which circuit breakers have more effective arc-extinguishing means, or are chutes, than prior art circuit breakers answering this description, and are therefore capable of having higher voltage ratings, current ratings and interrupting capacity ratings than comparable prior art circuit breakers.

Another object of the invention is to provide arc-extinguishing means capable of effecting progressive elongation of partial arcs while such arcs are caused to rotate by the action of magnetic fields.

Another object of the invention is to provide arc-extinguishing means capable of forming substantially U- shaped arcs and of progressively increasing the size and the length of substantially U-shaped arcs concomitant with a rotary motion thereof.

Another object of the invention is to provide simple and eifective arc-extinguishing means in stack-form capable of generating high arc voltages by simultaneous rotation and elongation of electric arcs.

Another object of the invention is to provide improved electric circuit interrupters wherein the opening, closing and normal current carrying duty is assigned to three different pairs of cooperating contacts.

Still another object of the invention is to provide improved electric circuit interrupters precluding excessive generation of heat between cooperating pairs of arcing contacts during initial separation of a pair of main current-carrying contacts.

Further objects, advantages and features of this invention will become apparent as the following description proceeds, and the features of novelty which characterize the invention will be pointed out with particularity in the claims annexed to, and forming part of, this specification.

For a better understanding of the invention reference may be had to the accompanying drawings, wherein Fig. 1 is mainly a front view of a circuit interrupter, or circuit breaker, embodying the invention showing some of the constituent parts, including a portion of the arc chute, in vertical section;

Fig. 2 shows a portion of the arc chute structure sectioned along IIII of Fig. 1;

Fig. 3 shows the left upper portion of Fig. 1 on a larger scale;

Figs. 5 to 7 are front views showing the contact structure of the circuit breaker illustrated in the previous figures in three different operating positions, Fig. 5 showing the closed contact position, Fig. 6 showing a position intermediate the closed contact position and the open con= tact position (the main current-carrying contacts being open and the arcing contacts being still closed) and Fig. 7 showing the open contact position resulting in complete cessation of current flow; and

Fig. 8 is a modification of the structure shown in Figs. 5 to 7 wherein the arcing contacts are separated when the current-carrying contacts are in their normal closed current-carrying position.

Referring now to the drawings, numeral 1 has been applied to indicate an operating rod for operating a contact arm 2 which is pivotally mounted at 3 and supports all the movable contacts of the circuit breaker. Contact arm 2. is provided with a four bar or pantograph linkage 14. Linkage 14 comprises four links shown in Fig. 1 to be arranged in the form of a parallelogram, and pivotally connected to each other at the ends thereof. Pantograph linkage 14 is pivotally supported by two links 41 pivotally mounted on contact arm 2. Contact arm 2 is provided with an oblique slot 43 receiving a guiding pin 42 of pantograph linkage 14. Pin 42 is hingedly mounted on the upper end of operating arm 1 to transmit the pull and push of arm 1 to pantograph linkage 14. It will be apparent that slot 43 and pin 42 jointly form a lost motion connection between parts 1 and 2, and parts 2 and 14, respectively. Reference numeral 19 has been applied to indicate the upper pin of pantograph linkage 14. A link 18 suspended on pin 19 supports at 17 a movable arcing contact 9 which includes the arc horns 10 and 11. Contact arm 2 supports the movable closing contact 4 adapted to engage the fixed closing contact 5, and contact arm 2 supports also the movable main current-carrying contact 6 adapted to engage the fixed main current carrying contact 7. The arc horns 10, 11 of movable arcing contact 9 are adapted to engage two arc runners 12, 13 which are also in the shape of arc horns. Arc runners 12, 13 transfer the are from the point of its initiation into an arc chute arranged at a point remote from the point of arc initiation and generally indicated by reference numeral 16. Any means known to be useful for the transfer of an are from the point of its initiation into an arc chute may be used to move the are extending between divergent arc runners 12, 13 into the arc chute 16-. One such means has been shown in the form of a family of magnetic plates 15 associated with each of the two are runners 12, 13. Arc transfer may also be expedited by pneumatic puffers, as is well known in the art. By virtue of the divergent arrangement of runners 12, 13 the arc is considerably elongated during its travel to and into arc chute 16. Are chute 16 is adapted to subdivide relatively long arcs into a plurality of serially related relatively short arcs, frequently referred to as partial arcs. Arc chute 16' is made up of a plurality of arc extinguishing parts arranged substantially in the form of a stack. These parts include solid arc runner rings 20 and are runner windings generally indicated by reference numeral 21. The parts referred to as arc runner rings are circular electrodes along which terminals of the partial arcs are caused to move in substantially circular paths. The parts referred to as are runner windings are windings for establishing magnetic fields substantially at right angles to some portion of the length of the partial arcs to cause circular rotary motions of the partial arcs. Windings 21 which are substantially circular are also used as electrodes along which terminals of the, partial arcs are caused to move in circular paths. In other words, windings 21 establish arc-propelling magnetic fields, and the surfaces thereof form are runners providing circular paths for are terminals. Each winding 21 comprises three turns 27, 31, 33. Each partial are 22 extends between one of the arc runner rings and one of the axially outer turns of one of the arc runner windings 21. An arcelongating barrier 23 of appropriateinsulating material is arranged between each arc runner ring 20 and each arc runner winding 21. Each barrier 23 projects radially outwardly beyond the periphery of arc runner rings 20 and are runner windings 21. Reference numeral 19' in Fig. 3 indicates the path of the are upon being elongated by the action of the arc runners 12, 13 but prior to being subdivided into a plurality of partial arcs. There is a point on the periphery of barrier 23 where its distance from the common axis of parts 20 and 21 is a minimum and another point where this difierence is a maximum (Fig. 2). The distance barrier 23 projects radially outwardly beyond the periphery of parts 20 and 21 increases progressively along the periphery of parts 20, 21 and 23. As shown in Fig.2 barrier 23 comprises two symmetrical portions for elongating partial arcs rotating in clockwise direction as well as for elongating arcs rotating in counterclockwise direction as will more clearly appear from what follows below. The long are 19 engages barriers 23 substantially at the point thereof where the distance said barrier projects radially outwardly beyond parts 20 and 21 is a minimum. At this point-the arc enters from the space between arc runners 12, 13 through the throat shown at the bottom of Fig. 2 into a plurality of arcing chambers 36 formed inside of arc chute 16. The relatively slight distance barrier 23 projects forwardly at the point of initial engagement thereof by long are 19 is sufiicient to bend are 19' at said point of initial engagement substantially in the shape of a relatively small or short U, as clearly indicated in the lower portion of Fig. 3. The lateral portions of the U- shaped partial arcs, i.e. the portions thereof situated immediately adjacent the arc terminals formed on parts 20 and 21, are substantially at right angles to magnetic fields produced by windings 21, and hence subject to magnetic action tending to impart a rotary motion to the partial arcs 22 as will be shown below more in detail. As the partial arcs 22 are caused to rotate, their terminals move along the periphery of parts 20 and 21, and the portions intermediate their terminals move along the edges of barriers 23. This causes progressive elongation of the partial arcs 22 by virtue of the progressive increase of the distance the arc-stretching periphery of each barrier 23 projects radially outwardly beyond the periphery of parts 20 and 21 or, in other words, beyond the common axis of parts 20 and 21.

Each magnet winding 21 is provided with a magnetic core 26 arranged along the axis of winding 21 substantially in the center thereof. Cores 26 are energized by the arc current flowing through windings 21. The axially outer ends of cores 26 are provided with pole plates 24 and 25 made of a suitable magnetic metal. Pole plates 24 and 25 are arranged inside of insulating barriers 23 and the shape of their periphery is similar to the shape of the periphery of barriers 23, a predetermined margin being left between the periphery of the former and that of the latter. The magnetic fields formed between pole plates 24 and 25 are substantially at right angles to pole plates 24 and 25, and at right angles to the portions of the partial arcs 22 which extend substantially radially outwardly from the arc terminals or are roots on parts 20 and 21.

The geometry of winding 21 can best be seen from Fig. 4 clearly showing the axially inner turn 31 and the two axially outer turns 27 and 33. Each turn is situated in a plane parallel to the planes of the other turns, i.e. the three constituent turns of winding 21 are not helical. As seen in Fig. 4 the left turn 27 is conductively connected to the intermediate turn 31 by a length of conductor 30 substantially at right angles to the planes of turns 27 and 31. Similarly, the intermediate turn 31 til) is conductively connected to the right turn 33 by a length of conductor 32 substantially at right angles to the planes of turns 31 and 33. As indicated in Fig. 3 adjacent windings 21 are wound in opposite directions, resulting in the formation of magnet poles of the same polarity at the juxtaposed ends of adjacent magnet cores 26. Reference letter S in Fig. 3 indicate a pair of juxtaposed magnet poles of the same polarity (south poles) on adjacent magnet cores 26. Reference letters N have been applied in Fig. 3 to indicate a pair of magnet poles of the same polarity (north poles) formed at the remote ends of immediately adjacent magnet cores 26. Reference numerals 28 and 34 indicate two are horns, the former being an integral part of turn 27 and the latter being an integral part of turn 33. Are horn 28 of turn 27 projects beyond the beginning of turn 27 and are horn 34 of turn 33 projects beyond the end of turn 33. A long are 19 rising into arc chute 16' engages initially winding 21 at the two points where are horns 28, 34 are situated. As a result, the portion of the are situated between arc horns 28 and 34 is being shunted by winding 21.

The are chute 16 further comprises a plurality of chambepforming units 35 made of an appropriate are resistant insulating material. Units 35 are superimposed, or stacked, as shown in Fig. 3. Units. 35 are provided with complementary recesses at some of their contiguous surfaces. These recesses form the arching chambers 36 of which each accommodates one of the arcelongating insulating barriers 23. The arcing-chamberforming stack units 35 are adapted to receive, and to house, the arc runner rings 20 and the arc runner wind ings 21. The portions of arcing-chamber-forming stack units 35 situated most remotely from the zone where the arc enters the arc chute define venting ducts to which reference numeral 37 has been applied (Figs. 2 and 3).. The abutting sides of units 35 opposite the arcing-chamher-forming recesses are provided with recesses forming pockets adapted to receive arcuate plates 38 of magnetic material. Plates 38 are arranged in every second plate receiving pocket, i.e. the magnetic plates are inserted into the pockets which are situated directly above the runner rings 20 but are not inserted into the pockets which are situated directly above the arc runner windings 21. Reference numeral 40 (Figs. 1 and 2) has been applied to indicate screws and studs projecting transversely across all the chamber-forming units 35 of the stack by which arc chute 16 is being made up. It will be apparent from the foregoing that all constituent parts of the arc chute 16 such as are runners 20 and 21, insulating barriers 23 and magnet cores 26 are properly positioned by parts 35 and 40. The barriers 23 are formed by transverse projections of tubular members on which parts 20 and 21 are mounted and which house the magnet cores 26. The aforementioned tubular members, cores 26 and parts 20, 21 are arranged in coaxial relation inside of a passage or tunnel defined by the stack units 35.

The contact arm may be rocked by operating lever 1 about fulcrum 3 in clockwise or counterclockwise direction (Fig. l). Rocking of arm 2 in counterclockwise direction results in parting of cooperating pairs of cont acts, drawing of an arc and eventual interruption of the circuit. Rocking of arm 2 from the open position shown in Fig. 7 in clockwise direction results in engagement of cooperating pairs of contacts and closing of the circuit which is controlled by the circuit breaker. A downward pull of operating lever 1 causes sliding of pin 42 inside slot 43 formed in contact arm 2. As a result, pantograph, linkage 14 is being moved from the position shown in Figs. 1 and 5 to approximately the position shown in Fig. 6. To be more specific, initial motion of operating lever 1 causes stretching of linkage 14 in a direction substantially transversely to that of arm 2 and a clockwise motion of the left link 41 supporting pantograph linkage 14. As a result of stretching linkage 14, contacts 10, 12 and'll, 13 remain in engagement while contacts 4, 5 and 6, 7 are caused to part. The aforementionedlink 41 and the immediately adjacent upper link of pantograph linkage 14 form jointly a toggle which is collapsed in the closed position of the circuit breaker (Figs. 1 and 5) and which is being drawn during the initial phase of the opening stroke of the circuit breaker, as indicated in Fig. 6. The aforementioned stretching of pantograph or four bar linkage 14 increases the spacing between arcing contact 9 and its arc horns 11, 12, on the one hand, and contact arm 2, on the other hand. The lower end of slot 43 forms an abutment 16 for pin 42. Upon engagement of abutment 16 by pin 42 arcing contact 9, 10, 11 and contact arm 2 move jointly about fulcrum 3. As a result of the aforementioned mode of operation the contact pressure between arc horns 10 and 11 of movable arcing contact9 and fixed arc runners 12, 13 may be increased during the initial phase of the opening stroke of operating lever 1, since the downward movement of pin 42- res'ults in an upward thrust of contact 9 and are horns 10, 11. Upon engagement of abutment 16 by pin 42 contact arm 2 is moved downwardly at a considerable speed, resulting in parting of arcing contacts 9, 10, 11 from are runners 12, 13 subsequent to parting of contacts 4, 5 and 6, 7. The small arclets initially formed between arc horn 10 and arc runner 12 and between arc horn 11 and are runner 13 merge instantly into a larger arc, extending between the lower ends of arc runners 12, 1 3. That are is propelled into arc chute 16 by thermal and magnetic effects or by auxiliary air blast action and thus reaches the position indicated in Fig. 3 by the reference character 19'. In that position the arc is situated at the entrance of the arc chute 16' proper. It has been stretched to a relatively long are by virtue of the divergence of arc runners 12 and 13. That long are is now about to be subdivided into a plurality of relatively short serially related partial arcs.

It appears from the foregoing that the contact pressure between arcing contact 9 and are runners 12, 13 may be greatly increased during the time of initial separation of contacts4, 5 and 6, 7 or, in other words, during the time when the entire current under interruption must be carried by arcing contact 9 only (Fig. 6). The pressure between arcing contact 9 and are runners 12, 13 increases in proportion to the friction at the hinge 3 of contact arm 2 and in proportion to the inertia of contact arm 2.

Whencontact arm 2 is being moved in clockwise direction from the open position shown in Fig. 7 to the closed position shown in Fig. 5 arcing contact 9 is the last to engage its cooperating contacts 12, 13 and thus relieved from carrying heavy inrush currents occurring upon closing the circuit breaker against a heavy fault or solid short-circuit. When operating lever 1 is being raised and contact arm 2 rocked in clockwise direction, pantograph linkage'14 is being compressed, as a result of which the contacts to first re-engage are the closing contacts 4, 5. The contacts to engage thereafter are the main current-carrying contacts 6, 7, and the contacts to close last are the arcing contact 9, 10, 11 and are runners 12, 13. Closing of contacts 6, 7 and 9, 10, 11, 12, 13 may occur in a very rapid sequence, or even simultaneously, as long as closing contacts 4, 5 have been closed first.

-Upon engagement of a relatively long are by the elements situated at the entrance of arc chute 16 proper, the long are is subdivided into relatively short substantially U-shaped arcs 22 which are connected in series by means of arc runner rings 20 and are runner windings 21. Immediately upon engagement by the partial arcs 22 of arc horns 28, 34 on arc runner winding 21 but the intermediate turn. 31 of winding 21 is being energized by the arc current. At this point of time, the arc terminals or are roots being. situated-on arc horns 28, 34. the current flows from the left are born 28 (Fig. 4) directly through conductor 30 to the intermediate turn 31, through the intermediate turn 31, and from the inter mediate turn 31 through conductor 32 directly to the right are horn 34. The magnetic fields resulting from current flow through turns 31 of windings 21 and concomitant energization of the magnet systems 24, 25, 26, is substantially at right angles to the portions of the partial arcs situated directly adjacent arc horns 28, 34. As a result, these portions of the arcs 22 are subjected to magnetic action tending to rotate these portions along circular paths. The partial arcs 22 are arranged edgewise with respect to the insulating arc-elongating barriers 23, and the curved portion of the partial arcs 22 engage the edges or the peripheries of barriers 23. This causes heat to be abstracted from the partial arcs 22. Since the distance barriers 23 project radially outwardly beyond the periphery of parts 20 and 21 increases progressively, the length and the arc voltage of partial arcs 22 are being progressively increased as these arcs are caused to rotate under the action of the magnetic fields which are established by winding 21. The length of the partial arcs increases as the arc terminals are moved in circular paths along the periphery of parts 20 and 21 away from their initial positions on arc horns 28, 34. Since the magneticaction upon a conductor is proportional to its length and since the length of partial arcs 22 increases progressively when moving along their circular paths, there is a tendency toward arc movement at progressively increasing speeds. The configuration of the spaces 36 defined between barriers 23 and arcing-chamber-forming stack units 35, i.e. the configuration of the arcing chambers is another significant factor in the process of arc extinction. Parts 23 and 35 may be designed to define spaces 36 which have drastic de-energizing effects upon the partial arcs 22 moving therein by virtue of intense cooling action resulting from an intimate contact of the are 22 with parts 23 and 35, and resulting from an arc constricting action of these parts.

It will be apparent from the geometry of the magnetic structures and that of the magnetic fields as indicated in Fig. 3 that immediately adjacent partial arcs 22 rotate in opposite directions rather than in the same direction. The direction of rotation of the arc terminals or are roots has been indicated by arrows in Fig. 4. It will be seen that are terminals formed on are horns 28 of axially outer turns 27 are caused to rotate clockwise, while the arc terminals formed on the arc horn 34 of axially outer turns 33 are caused to rotate counter-clockwise.

As mentioned above, no current flows through the axially outer turns 27, 33 during the initial stage of arc rotation. The more remote the arc terminals from are horns 28 and 34, the larger the portions of turns 27 and 33 connected in series with turn 31 to produce the arcrotating magnet field. This tends to cause a progressive increase of the action of the magnetic field upon the rotating partial arcs 22. Upon completion of each revolution the arc terminals rotating along the surfaces of parts 20 and 21 are transferred back to are horns 28 and 34 respectively. At the instant of the transfer of the arc terminals back to the arc horns 28, 34 the axially outer turns 27, 33 are again out out of the circuit which then comprises but parts 30, 31 and 32. Arc horns 28 and 34 preclude the erosion of the surfaces of turns 27 and 33 on which the arc terminals move. Such erosion tends to impede the desired high-speed rotary motion of the terminals of the partial arcs 22 along parts 27, 33.

As a general rule, the various partial arcs 22 do not rotate in phase and synchronism along their rotary paths. This has been found to be beneficial to the arc-extinguishing action of arc chute structure 16.

It will be apparent that but a portion of the partial arcs 22 is situated inside of the magnetic fields established between pole plates 24 and 25. The portion of the partial arcs 22 immediately adjacent the parts 20 are not sub jected to the action of the magnet field established be-- ""7 tween pole plates 24 and 25. These portions of the partial arcs 22 are subjected to the action of magnetic fields established between pole plates 24 and 25 and the magnetic plate inserts 38.

In the structure which has been described above the magnetic fields required for arc rotation are solely established by electromagnetic means. As an alternative such fields may also be established wholly, or partly, by the action of permanent magnets.

The contact mechanism shown in Figs. to 7 may be modified in such a way as to cause arcing contact 9 not to engage its cooperating fixed contacts 12, 13 as long as the closing contacts 4, 5 and the main current-carrying contacts 6, 7 are in engagement. This modification has been illustrated in Fig. 8. In the structure shown in Fig. 8 contacts 9, 12, 13 are not normally carrying current. Contacts 9, 12, 13 are caused to engage only upon occurrence of a tripping impulse causing operating rod 1 to move in downward direction. This causes elongation of the four bar linkage 14, concomitant increase of the spacing between arm 2 and contact 9, and ultimate engagement of runner contacts 12, 13 by the arc horns of arcing contact 9. Contacts 9, 12, 13 are caused to engage before either contacts 4, 5 or contacts 6, 7, separate. At the time of engagement of contacts 9, 12, 13 these contacts are cool, not having been subjected to any previous current-carrying duty. No arcing occurs when contacts 9, 12, 13 are being closed since these contacts are then shunted by contacts 4, 5 and 6, 7. The pressure of arcing contact 9 upon runner contacts 12, 13 tends to move contact arm 2 counterclockwise, or in circuit interrupting direction. This is true in regard to the embodiment of the invention shown in Fig. 8 as well as to that shown in Figs. 1 and 5 to 7.

It will be apparent from the foregoing that the arc chute or arc-extinguisher 16' according to this invention comprises a plurality of stacked insulating units 35 having complementary arcing-chamber-forming recesses 36 at some contiguous sides thereof. The stack of units 35 defines also a passage or tunnel which extends transversely across the stack. The aforementioned passage or tunnel receives a plurality of substantially tubular coaxial members of insulating material, arranged in coaxial relation in regard to said passage or tunnel. Contiguous pairs of these tubular members are each provided with one of a pair of transverse, abutting barrier-forming projections 23. Each of projections 23 extends from the outer surfaces of contiguous pairs of the tubular members into contiguous pairs of arc-chamber-forming recesses 36 in units 35. The periphery or edge po'rtion of each projection 23 comprises a point having a predetermined minimum distance or spacing from the axis of the aforementioned tubular members, and the periphery or edge-portion of each projection 23 further comprises a point having a predetermined maximum distance or spacing from said axis. The distance or spacing of intermediate points of said periphery or edge-portion from said axis increases progressively from said first mentioned point to said last mentioned point. The plates 24, 25 of magnetic material are arranged between some of the juxtaposed surfaces of barrier-forming projections 23. The annular arc runners 20, 21 are mounted on the outside of the aforementioned tubular members, their inside forming housings for cores 26. Each core 26 magnetizes plates 24, 25 and 38. The magnetic fields established between plates 24, 25 and 38 rotate the partial arcs 22 formed in arcing chambers 36. Rotation of arcs 22 in engagement with edges of barriers 23 results in progressive arc elongation, and ultimate arc extinction.

The are as initially drawn is situated substantially in a predetermined plane, which is the plane of the paper on which Fig. 3 is drawn. Barriers 23 and their periphery (see Fig. 2) are symmetrical in regard to the plane in which the arc is initially drawn, the latter plane being at '8 right angle to the plane of the paper on which Fig. 2 is drawn.

It will also be noted that magnetic plates 25 and 28 are situated in parallel planes.

Referring now to Fig. 8, the lost motion connection between arm 2 and the pantograph linkage which is supported by said arm defines two limit positions for the pantograph linkage relative to arm 2. The first of these two limit positions is illustrated in Fig. 8. In the limit position illustrated in Fig. 8 contacts 9, 12, 13 are out of engagement, while contacts 4, 5 and 6, 7 are in engagement. In the second limit position contacts 9, 12, 13 are in engagement, while contacts 4, 5 and 6, 7 are out of engagement.

It will be apparent to those skilled in the art that various changes and modifications may be made in the circuit breaker structure described and illustrated without departing from the spirit of the invention, as set forth in the appended claims.

I claim as my invention:

1. In a circuit interrupter the combination of means for drawing an arc, means for establishing a magnetic field at right angles to a portion of said arc to impart to said are a rotary motion in a predetermined direction, a pair of spaced substantially coaxial electrodes providing substantially circular paths for the terminals of said arc, and an insulating barrier arranged in the space between said pair of electrodes edgewise with respect to said arc, said barrier projecting in said predetermined direction progressively farther outwardly from the axis of said pair of electrodes to progressively elongate said are when rotating.

2. In a circuit interrupter the combination of means for drawing an are, means including a pair of divergent arc runners for moving said arc away from the zone of arc initiation and for elongating said arc, a stack formed of hollow elements of insulating material defining a line of contiguous arcing chambers having arc entrances at the sides thereof adjacent said pair of arc runners, means for subdividing said are when at said are entrances into a plurality of serially related partial arcs, means including magnetic means for rotating each of said plurality of partial arcs inside one of said plurality of arcing chambers about a common axis, and a plurality of insulating barriers one in each of said plurality of arcing chambers, each of said plurality of barriers having an arc-stretching periphery, consecutive points of said periphery having progressively increasing spacings from said common axis.

3. In a circuit interrupter the combination of means for drawing an are initially situated substantially in a predetermined plane, a first substantially annular electrode having a predetermined outer radius and adapted to provide a circular path for one terminal of said arc, a second substantially annular electrode having a predetermined outer radius and adapted to provide a circular path for the other terminal of said arc, said second electrode being arranged in coaxial relation with respect to said first electrode and being in the form of a winding having more than one turn, a magnetic core inside said winding energized by electric current flowing through said winding, magnetic pole plates at the axially outer ends of said core establishing a magnetic field for rotating said are about the axis of said first electrode and of said second electrode, and an insulating barrier arranged in the space between said first electrode and said second electrode substantially at right angles to said axis, the periphery of said barrier comprising two portions symmetrical in regard to said predetermined plane wherein said are is initially situated, consecutive points of each of said portions having progressively increasing spacings from said axis, the minimum spacing of said portions from said axis exceeding the outer radii of said first electrode and of said second electrode, the point of said periphery having said minimum spacing being that point of said periphery situated nearest to said means for drawing an arc.

4'. In a circuit interrupter means'for drawing a pair of arcs, a pair of; spaced substantially annular coaxial electrodes providing circular paths for two terminals of said pair of arcs, an additional substantially annular coaxial electrode arranged in the space between said pair of electrodes, said additional electrode being in the form of awinding having a pair of axially outer circular arc-pathforming turns and an axially inner turn connected in series with said two serially outer turns, a magnetic core inside said axially outer turns and said axially inner turn, a pair of insulating barriers each arranged in the space between one of said' pair of electrodes and one of said pair of axially outer turns substantially at right angles to the axis of said pair of electrodes and of said additional electrode, each of said pair of barriers comprising an edge-like arcstretching-portion, consecutive points of said portion having progressively increasing spacings from said axis, and a pairof magnetic poleplates one inside ofeach of said pair'of barriers, each of said pair of poleplates being inv engagement with one of the axially outer ends of said core andestablishing a magnetic field substantially parallel to said" axis.

5'. In a circuit interrupter a plurality of substantially tubular coaxially arranged members of insulating material provided with transverse radially outer barrier-formingprojections having a predetermined periphery, consecutive points of said periphery having progressively increasing spacings from the axis of said plurality of members, a plurality of spaced magnetic cores arranged inside said plurality of members, pairs of magnetic pole plates on the axially outer ends. of each of said plurality of cores, each of said pairs of pole plates extending into the inside of one of said barrier-forming projections, a plurality of spaced windings mounted on the outside of said plurality of members each for energizing one of said plurality of cores therein, each of saidplurality of windings comprising a pair of axially outer turns adapted to form substantially circular arc. runner surfaces, and a plurality of additional windings mounted on the outside of said plurality of members, forming substantially citcular' additional arc runner surfaces, each of said barrierforming projections separating one of said are runner surfaces from oneof said-additional, arc runner surfaces.

61 In a circuit interrupter means for drawing a relatively short are, arc elongating means transferring said are from, the point of arc initiation to a point remote therefrom, arc-quenching means at. said remote point, said arc-quenching means including a plurality of stacked insulating units having complementary arcing-chamberforming recesses at contiguous sides thereof, said plurality. of units also defining apassage extending transversely across said plurality of units, a plurality of substantially coaxial members of insulating material arranged inside said passage, contiguous pairs of said plurality of members each being provided with one of a pair of transverse abutting barrier-forming projections, each of said pair of barrier-forming projections extending from the outer surfaces of a contiguous pair of said plurality of members into a contiguous pair of said recesses, the periphery of each of said pair ofbarrier-forming projections comprising a point having a predetermined minimum distance from the axis of said plurality of members and further comprising a, point having a predetermined maximum distance from said axis, the distance of intermediate points of said periphery from said axis progressively increasing from said first mentioned point to said last mentioned point, plates of magnetic material arranged between the juxtaposed surfaces of each of said pair of barrier-forming projections, a plurality of substantially annular arc runners mounted on the outside of said plurality of members, said plurality of arc runners being adapted to subdivide said are into a plurality of partial arcs and to provide circular paths for the terminals of said partial arcs, and a plurality of spaced magnet cores mounted inside said plurality of members each adapted to energize a pair of said plates of magnetic material to establish mag- 10 netic fields between pairs of said plates to cause said plurality of partial arcs to rotate around said plurality of arc runners to thereby elongate said plurality of partial arcs.

7. A circuit interrupter as specified in claim 6 wherein some of said plurality of arc runners comprise several turns, and wherein each of said plurality of arc runners comprising several turns is mounted directly above one of said plurality of magnet cores to energize said one of said plurality of magnet cores, and wherein contiguous surfaces of said insulating units are provided with recesses adapted to receive additional plates of magnetic material situated in planes parallel to the planes defined by said plates of magnetic material.

8. In a circuit interrupter the combination of a pair of cooperating separable main current-carrying contacts, a pair of cooperating separable arcing contacts, joint contact separating means for one of said pair of main currentcarrying contacts and one of said pair of arcing contacts, said joint contact separating means including means for causing separation of said pair of main current carrying contacts prior to separation of said pair of arcing contacts, and means tending to increase contact pressure between said pair of arcing contacts during initial separation of said pair of main current-carrying contacts preparatory to separation of said pair 'of arcing contacts.

9. A circuit interrupter as specified in claim 8 comprising a common support for one of said pair of main current-carrying contacts and for one of said pair of arcing contacts, separating means interposed between said common support and said one of said pair of arcing contacts to increase the spacing between said common support and said one of said pair of arcing contacts, an operating rod for operating said separating means to increase said separation, and a lost motion connection between said common support and said operating rod to enable said operating rod to effect joint opening movement of said one of said pair of main current-carrying contacts and of said one of said pair of arcing contacts in addition to increasing said separation.

10. In a circuit interrupter the combination of a pair of cooperating relatively movable main current-carrying contacts, a pair of cooperating relatively movable arcing contacts, a support for one of said pair of main currentcarrying contacts, a pantograph linkage supported by said support and supporting one of said pair of arcing contacts, pantograph linkage operating means for causing movement of said pantograph linkage and of said one of said pair of arcing contacts relative to said support to increase the spacing between said one of said pair of arcing contacts and said support, and a lost motion connection between said operating means and said support to enable said operating means to effect joint movement of said pantograph linkage and said support upon initial movement of said pantograph linkage relative to said support.

11. In a circuit interrupter the combination of a pivotally mounted contact support, a movable main currentcarrying contact supported by said support, a fixed main current-carrying contact adapted to cooperate with said movable main current-carrying contact, a fixed arcing contact, a movable arcing contact adapted to cooperate with said fixed arcing contact, a four ba linkage supporting said movable arcing contact supported by said sup port, said four bar linkage comprising a pin guided in a slot provided in said support and adapted upon operation thereof to vary the spacing between said movable arcing contact and said support, and an operating rod journaled to said pin. Y

12. In a circuit interrupter a pivotally mounted contact support, a movable circuit closing contact mounted on said support, a fixed circuit closing contact adapted to cooperate with said movable circuit closing contacts, a movable main current-carrying contact mounted on said support, a fixed main current-carrying contact adapted to cooperate with said movable main current-carrying contact,

a pair of fixed horn-shaped arc runners, a horn-shaped movable arcing contact adapted to cooperate with said pair of arc runners, a four bar linkage supporting said arcing contact, a pair of links pivotally mounted on said contact support supporting said linkage, cooperating abut ment means on said linkage and on said support limiting realtive movement between said linkage and said support, and an operating rod pivoted to said linkage for operating said linkage and said support to cause movement of said linkage relative to said support and joint movement of said linkage and said support.

13. In a circuit interrupter a first pair of relatively movable contacts; a second pair of relatively movable contacts; a third pair of relatively movable contacts; contact opening means for said first, second and third pair of contacts adapted to open said third pairs of contacts subsequent to opening of said first pair of contacts and opening of said second pair of contacts; and contact closing means adapted to close said first pair of contacts prior to closing of said third pair of contacts, said contact opening means and said contact closing means including means for causing joint movement of one of said first pair of contacts, one of said second pair of contacts, and one of said third pair of contacts, and said contact opening means and said contact closing means further including means for causing relative movement between said one of said first pair of contacts and said one of said second pair of contacts.

14. In a circuit interrupter a fixed main current-carry ing contact, a contact support, a movable main currentcarrying contact fixedly mounted on said contact support and adapted to cooperate with said fixed main currentcarrying contact, a fixed arcing contact, a movable arcing contact adapted to cooperate with said fixed arcing contact, a linkage supporting said movable arcing contact and being supported by said contact support, said linkage being adapted to vary the spacing between said movable arcing contact and said contact support, and operating means for said contact support and for said linkage including an operating rod hingedly connected to said linkage and a lost motion connection between said linkage and said contact support.

15. In a circuit interrupter a first fixed contact, a first movable contact adapted to cooperate with said first fixed contact, a support for said first movable contact, operating means for said support adapted to selectively exert a force upon said support in a first direction and in a second direction to separate said first movable contact from said first fixed contact and to engage said first fixed contact by said first movable contact, a second fixed contact, I

a second movable contact arranged a variable distance from said support and adapted to cooperate with said second fixed contact, contact supporting means supported by said support supporting said second movable contact, said contact supporting means being adapted to increase said distance when acted upon in said first direction and to decrease said distance when acted upon in said second direction, means for securing said operating means to said contact supporting means, and a lost motion connection between said contact supporting means and said support to enable relative and joint movement of said first movable contact and of said second movable contact by said operating means.

16. In a circuit interrupter a first fixed contact, a first movable contact adapted to cooperate with said first fixed contact, a support for said first movable contact, operating means for said support adapted to selectively exert a force upon said support in a first direction and in a second direction to separate said first movable contact from said first fixed contact and to engage said first fixed contact by said first movable contact, a second fixed contact, a second movable contact arranged a variable distance from said support and adapted to cooperate with said second fixed contact, means for varying said distance including a pantograph linkage supported by said support supporting said second movable contact, said linkage being adapted to increase said distance when acted upon in said first direction and to decrease said distance when acted upon in said second direction, means for securing said operating means to said pantograph linkage, anda lost motion connection between said support and said pantograph linkage to enable relative and joint movement of said support and of said pantograph linkage by said operating means.

17. In a circuit interrupter a fixed current-carrying contact, a movable current-carrying contact adapted to cooperate with said fixed current-carrying contact, a pivotally mounted arm supporting said movable currentcarrying contact, an operating rod for said arm adapted to selectively exert a force upon said arm in a first direction and in a second direction to separate said movable current-carrying contact from said fixed currentcarrying contact and to engage said fixed current-carrying contact by said movable current-carrying contact, a fixed arcing contact, a movable arcing contact adapted to cooperate with said fixed arcing contact, means for varying the spacing between said movable arcing contact and said arm including a pantograph linkage supported by said arm supporting said movable arcing contact, said pantograph linkage being adapted to increase said spacing when acted upon in said first direction and decrease said spacing when acted upon in said second direction, means for securing said operating rod to said pantograph linkage, and a lost motion connection between said arm and said pantograph linkage, said lost motion connection determining a first limit position of said pantograph linkage relative to said support wherein said movable arcing contact is separated from said fixed arcing contact while said movable current-carrying contact is in engagement with said fixed current-carrying contact, and said lost motion connection further determining a second limit position of said pantograph linkage relative to said support wherein said movable arcing contact is in engagement with said fixed arcing contact while said movable current-carrying contact is out of engagernent with said fixed current-carrying contact.

References Cited in the file of this patent UNITED STATES PATENTS 1,840,292 Slepian Jan. 2, 1932 2,099,607 Huttinger Nov. 16, 1937 2,100,743 Johnson Nov. 30, 1937 2,538,370 Lerstrup Ian. 16, 1951 2,783,336 Latour Feb. 26, 1957 FOREIGN PATENTS 162,128 Great Britain Apr. 28, 1921. 

